In an image forming material comprising a necessary layer on a support (for example, a silver halide light-sensitive material, a sheet used in a ink jet, a diffusion transfer image forming material and its receiving sheet, etc.), in recent years, enhancing an endurance has been demanded. Improvement of a layer peeling caused by with passage of time or by addition of strong power has been demanded. A hydrophilic colloidal layer constituting the silver halide photographic light-sensitive material is mainly composed of gelatin. However, when surface of the light-sensitive material is rubbed against foreign matter by virtue of weak force by which the hydrophilic colloidal layer is not destroyed, pressure is given to a silver halide through the gelatin which is binder to result in fog.
Various improvements of fogging by pressure have been proposed. For example, a method for increasing an amount of binder in a silver halide emulsion layer, a method for adding polymer latex to the emulsion layer described in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP-A) No. 50-56227, a method for adding high boiling organic solvent to the emulsion layer described in JP-A Nos. 53-13923, 53-85421, a method for adding colloidal silica to the emulsion layer, a method for adding composite latex to the emulsion layer described in JP-A No. 1-177033, and a method for adding polymer latex containing an active methylene group to the emulsion layer described in JP-A Nos. 7-295130, 7-239523, are known. However, since still more toughness has been required in the silver halide photographic light-sensitive material, by these technique mentioned above, sufficient effect can not be obtained, furthermore storage stability and covering power tend to decrease.
A method for increasing intensity of wet gelatin membrane by adding the polymer latex containing the active methylene group to the light-sensitive material has been proposed in Japanese Patent Examined Publication Nos. 45-5819, 46-22507, JP-A Nos. 50-73625, 8-248548, 8-201950. Further, as active methylene latex polymerized in the presence of water soluble polymer, copolymerized latex derived from vinylacetate and monomer containing the active methylene group is described in JP-A 52-22030. However, there is no applied example in which the copolymerized latex derived from vinylacetate and monomer containing the active methylene group is employed in the light-sensitive material.
The inventors of the present invention examined improvement of the silver halide fog occurred by pressure generated by rubbing without decrease of storage stability and covering power, employing latex containing active methylene groups and found that active methylene latex polymerized in the presence of water soluble polymer could improve not only fogging by pressure but also storage stability and covering power.